The present invention generally relates to aviation electronics, and more particularly relates to cockpit controls for avionics equipment, and even more particularly relates to methods and systems for illuminating mechanical rotary push-button switches in an aircraft cockpit.
In recent years, the Federal Aviation Administration (FAA) has begun requiring that all mechanical rotary switches which have push buttons be lighted for easier viewing in low light and other conditions. Avionics engineers are constantly striving for improvements which either reduce the weight of an airborne device, reduce its cost or power consumption, or increase its reliability. Often, avionics engineers must make design trade-offs among these often conflicting goals. One such example is the prior art mechanical-to-electrical rotary switch which is lighted via a lamp disposed on the panel end of the switch rotary shaft. Typically, this lamp is powered by a wire or an integral electrical trace which is formed into the switch. This lamp is used to illuminate the entire panel end of the button. While these illuminated lamps have been used extensively in the past, they do have some drawbacks. First of all, they often have leakage problems which result in bright light being emitted in the cockpit in the gaps around the periphery of the button. They also often have reliability problems if the lamps are disposed near the buttons where they may have inadequate heat transfer structure. This results in either hot buttons or a hot environment about the lamp, which can lead to lamp failures. Alternatively, these switches can be made to be free from leakage and/or more reliable, but then often a relatively high cost and with more weight.
Consequently, there exists a need for improved methods and systems for illuminating, in an efficient manner, a mechanical-to-electrical rotary switch which has a push button.
It is an object of the present invention to provide a system and method for illuminating a mechanical-to-electrical rotary switch in an efficient manner.
It is a feature of the present invention to utilize a hollow switch rotating shaft.
It is another feature of the present invention to include a fiber optic cable disposed within said hollow shaft.
It is another feature of the present invention to power the illumination of the switch from an avionics line replaceable unit (LRU), which is coupled to and receives signals from the rotary switch.
It is an advantage of the present invention to achieve improved efficiency in illuminating rotary switches.
It is another advantage of the present invention to visually indicate a loss of power in the avionics LRU which receives signals from the switch.
It is another advantage of the present invention to reduce the amount of leakage of unwanted light into the cockpit.
The present invention is an apparatus and method for illuminating a mechanical-to-electrical rotary switch, which is designed to satisfy the aforementioned needs, provide the previously stated objects, include the above-listed features, and achieve the already articulated advantages. The present invention is carried out in a xe2x80x9cleakage-lessxe2x80x9d manner in a sense that the light leakage about the periphery of the button has been greatly reduced.
Accordingly, the present invention is a system and method including a mechanical-to-electrical rotary switch, having a hollow switch shaft with an optical fiber disposed therein.